Lesson 2: Window Retrofitting v2

Existing conditions to be retrofitted.

Carefully remove existing trim and try to salvage for use after new window is installed.

• Remove existing window.

• Adjust framing as necessary to make opening square and allow for 1/2” of space around window frame.

• If adding a sloped sill, be sure to account for the height of the sloped sill in addition to the 1/2” of space on each side of the window casing.

• Apply Joint & Seam Filler to corners, intersections, and edges of opening.

• Tool into place.

Apply FastFlash around inside of opening and extend out as far as possible from opening on face of sheathing.

Lift up any existing building paper and continue FastFlash out as far as possible.

When possible, bring FastFlash out over the top of siding for continuous lapping (shown with window installed).

• Use shims to leave a space between the bottom flange and building frame to allow drainage in case of window failure.

• 1/16” to 1/8” horseshoe shims are recommended.

Install window in RO and fasten per manufacturer specifications.

• Bead and tool Joint & Seam Filler along top window flange to prevent water intrusion.

• Optional (pictured): Apply Joint & Seam Filler to jambs as well, but NEVER to sill.

Install head flashing to protect the trim.

• Complete the window retrofit by fitting trim and caulking around edges where the trim meets the siding on the sides, but NEVER the bottom.

• Kerf bottom of sill trim with a 3/16” drip edge.